We upgraded to 2013 three weeks ago. I noticed a significant slow down in performance. I found a article on the web to optimize the system options, and that helped with zooming/rotating the model, but I noticed adding a part, deleting a part, mating, or copy with mates was painfully slow, like 15 seconds per mouse click operation. Reinstalled, cleaned up the system, researched, researched and researched more.

The issues I seemed to be having was with one particular assembly, but that was really the only big project I was working on at the time. I had added a Center of Mass Feature, but I had suppressed it thinking it might slow things down. Finally I just deleted the feature from the feature tree, and bam, issue solved. I guess it must still be constantly updating the CoM even when it is suppress. Bug?

Admittingly our machines are not SW certified performers, that they recommend, but we had no issues at all in 2012.

Hopefully this might help someone that has the same issue.